Many types of Self-Service Terminal (SST) are known whereby transactions are carried out at the SST by a user to receive and/or deposit items of media. For example, an Automated Teller Machine (ATM) is an example of an SST and it is known that users of ATMs can use such machines to deposit and/or withdraw currency notes. The control and operation of an ATM is complex and thus ATMs can be costly to manufacture and operate. Conventionally, a central processor and local data store (typically a disk drive) are provided in an ATM and the data store stores an Operating System (OS) and ATM application used by the ATM. This makes updating the operations which can be carried out at an ATM a time consuming and costly process because ATMs must be updated individually each time a change to the OS or ATM application is to be implemented.